The packing density of electronic components on chips continues to rise, thereby increasing the energy dissipation per unit surface area. In order to decrease the resulting high temperatures, fluid filled microchannel devices are used for thermal energy transport. Previous microchannels have had limited channel shapes or configuration of shapes to increase the heat removal capacity. Past investigations of microchannel with forced convective flows have used rectangular channel shapes. Normal heat removal rates are on the order of 3.4 W/cm2-° C. This low heat transfer rate forces electronic components to operate at high temperatures with reduced operational life.
The capability of cooling technology for leading-edge microelectronic products is being pushed to the limit due to the ever-increasing heat flux generating components mounted on high-density electronic chips. In order to remove the large heat fluxes generated by these components, two-phase devices, such as heat pipes and two-phased pumped fluid loops with a single microchannel, are being considered. Microchannel heat sinks for high heat flux electronic cooling has been used. The heat removal capability of such microchannel devices is based on the large heat transfer surface-to-volume ratio of microchannels. High single-phase heat transfer coefficients can be achieved at the expense of enormous pressure drops in microchannels. Two-phase flow microchannel heat sinks are capable of removing heat fluxes generated by high density packages in excess of 200 W/cm2. The major disadvantages associated with the use of two-phase cooling devices is that the system needs to avoid instability when operating close to the critical heat flux point and needs to minimize surface temperature gradients between the microchannel and the upper surface of the heat sink.
The single-phase loops have incorporated methanol, refrigerant-124, FC-87, and water. With water as the working fluid, a heat flux of 790 W/cm2 could be dissipated in a rectangular grooved microchannel. The corresponding substrate temperature rise was 71° C. above the input water temperature. This represented a maximum downstream thermal resistance of about 0.09° C./W for a 1.0 cm2 heated area. Both laminar and turbulent flow regimes offer a method to lower the total thermal resistance of a microchannel. Two analytical approaches have been employed to evaluate the velocity profile of microchannel flows. One method is a microanalysis method in which the microchannels are independently investigated. The second method is a macroanalysis method that simulates the microchannel stream as a flow through a porous media and typically incorporates a volume-averaging technique and a form of the Darcy equation. The macroanalysis method requires a uniform cross section. Thus, any geometric channel shape that would cause porosity to be a function of one or more coordinate axes is not an appropriate usage of the porous material analysis assumption. Microchannel heat removal processes and simulations have been used to accurately model and simulate the volume flow rates for heat removal performance verification.
Microprocessor components, such as silica chips, are generating high heat flux levels. This corresponds to high temperatures and the corresponding reliability issues for these devices. Optimization of rectangular shaped microchannel grooves utilizing water as the pumped single phase fluid have been used in order to decrease the temperature of microprocessor components. Heat transfer solutions from rectangular microchannel shapes for heat sinks have limited energy transfer rates. While extensive work exists for the rectangular microchannel cross sectional area, the rectangular microchannel cross sectional area offers increased packing density with large flow rates but with limited heat transport capabilities. These and other disadvantages are solved or reduced using the invention.